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Biological Magnification
Cycle
What is Biological Magnification? Biological Magnification, also known as
Biomagnification, is the increase of substances that occurs in food chains.
These substances are usually found in contaminated
environments. Substances, such as pesticides and mercury, are absorbed by organisms due to their environment or the food they consume. The substance then accumulates inside the cells.
When an organism higher in the food chain eats multiple organisms below, each of them containing some of the toxins, the toxins becomes more concentrated in the higher food chain. Since this continues throughout the food chain, organisms higher in the food chain are the ones who will obtain the most toxins.
Bioaccumulation Biological Magnification is often related with
Bioaccumulation, which is the increase of the toxic substance in an organism’s body.
These two terms are different:
o Accumulation pertains to harmful substances in a living organism's body and its effects.
oMagnification deals with the substance being passed along the food chain.
Bioaccumulation will cause a number of problems within the body that contains it.
How Biomagnification affects animals A common example of Bio magnification and Bioaccumulation is
the use of DDT in the 1960's and 1970’s. DDT, or dichlorodiphenyltrichloroethane, was overly used by humans as a pesticide. It soon found its way into the environment.
DDT and other toxins eventually climbed up the food chain, and
affected the bald eagles, nearly driving them to extinction. The DDT was absorbed by organisms which the bald eagles hunted, such as fish and carrion. Each bald eagle would eat multiple numbers of these fish and carrion.
The DDT would accumulate inside each of the eagles' bodies.
The DDT would sterilize the birds or cause them to make fragile eggs that would break easily. This caused the birds population to dwindle rapidly.
Bald Eagle Population
http://www.fws.gov/midwest/eagle/population/chtofprs.html
Figure 1
How DDT rises in a food chain
Mercury Mercury is a natural substance, that is found in very
small quantities in the ocean. Human interference with the environment, causes higher levels of mercury in the ocean.
Algae, a producer, consistently absorbs the mercury
which is found in its environment. However, it excretes it slowly. Often, zoo plankton will consume the algae and the mercury along with it.
The plankton is then consumed by small fish, which is
in turn consumed by larger fishes. Eventually, the fishes end up on human dinner tables. Humans, who consume fishes high in mercury, will easily become ill from mercury poisoning.
Biological Magnification of Mercury
The Biological Magnification of DDT in a marine ecosystem.
Toxins that Bio magnify
DDT and Mercury are not the only toxin that biomagnifies. Other examples include, but are not limited to:
PCB'S (polychlorinated biphenyls): used in insulators, as a plasticizer, and fire retardant. It biomagnifies, impairs reproduction and is widespread in aquatic systems.
Cyanide is used in leaching gold and in fishing. It is a dangerous
toxin and is known to have effects on coral reefs.
Selenium is concentrated by farming desert soils. It is toxic and causes reproductive failures in organisms.
Heavy metals such as mercury, copper, nickel, zinc, and lead
affect the nervous system and they may affect reproduction.
More Biological Magnification
http://jan.ucc.nau.edu/~doetqp-p/courses/env470/Lectures/lec39/Lec39.htm
Figure 5
Why We Should Care Ironically, bio magnification and bioaccumulation are
caused by humans but also have a profound impact on us.
It can lead to neurological effects such as mental
retardation in infants who contract it through their mothers.
A weakened immune system is also the result of bio
magnification.
Some cancers are also linked through ingesting these toxins.
It can also lead to organ failure in both animals and humans.
Since some animals have weaker immune systems then humans, they will die faster which can lead to extinction if it continues.
Prevention of Bio magnification In an attempt to eradicate bio magnification, the U.S. and
several countries worldwide have placed a ban on the use of DDT.
People are trying to prevent harmful substances such as oil
and human waste from being dumped in water.
Landfills are also trying to get rid of these substances because they can seep into ground water.
Special Thanks / Citations
Information
http://en.wikipedia.org/wiki/Biomagnification
http://toxics.usgs.gov/definitions/biomagnification.html
http://www.marietta.edu/~biol/102/2bioma95.html
http://www.epa.gov/med/grosseile_site/indicators/erie_fish.html
http://jan.ucc.nau.edu/~doetqp-p/courses/env470/Lectures/lec39/Lec39.htm
Special Thanks / Citations Continued
Pictures
http://www.calgoldrush.com/graphics/images/contamination.gif
http://image.wistatutor.com/content/ecosystem/biological-magnification.jpeg
http://www.corg/html/stitch.php?s=98965698293378&id=34347859802049fkeep.
http://www.fws.gov/midwest/eagle/population/chtofprs.html
PREPARED BY: ANGELIKA OLBOC
BIOLOGICAL SCIENCE MAJOR